feat: migrate from cocoapods-keys to ArkanaKeys

[NanoSector]

Fixes #483

[CLAassistant]

All committers have signed the CLA.

[MainasuK]

Oops. Thank you for your PR about secret injection improvement.
But the migration is already implemented in #477
I'll try to migrate it quickly.

To make things clear. I need to explain there are several refactor workings on going.

1. New app structure with AuthContext helps the app manage multiple account authentications. This is an idea from Multiple Windows support on iPadOS #435
2. Release v1.4.6 #469 release branch code base migrate back
3. The new compose scene with SwiftUI. This helps the app use the same UI/UX for share extension.
4. The post-edit feature [WIP] Add post edit feature #475

I'll resolve tasks 1 and 2 soon to ensure the git-flow is not blocking PR.

[NanoSector]

Thanks for your reply, I was unaware of this.

As it stands, that PR is currently blocking every contribution to this repository, and the repository itself cannot be built at all at the moment on newer Xcode versions.

I would suggest that we at least merge this PR to return the project to a buildable state, seeing as your PR is very large and it is unknown when it will be merged.

I would also suggest splitting up your PR into smaller branches if possible to ease the migration; if you'd like this, I would like to help with that.

[MainasuK]

Now the develop branch should be stable for contribution although the compose scene feature not fully restored. I'll be working on #493 and I'll take care PRs if has any conflicts. You can just ignore confilect in other PRs. And this PR will be closed due to arkana is ready now. see here

The #477 refactor is just inject the AuthContext component in the app lifetime to remove redundant authentication check logic. Also, the core logic is grouped in SPM as packet. I hope that 10000+ changes not too scare…

I have not expected that there are lots of PRs coming. I'm not fully available in this project because I need complete my main job then contributes to this repo.

And thank you for your contributions.

[NanoSector]

Thanks for the quick resolve, I'll check if I can update my other PR with the changes.